The Hervey Bay ambos met the couple on Monday, October 22, presenting them with two paramedic teddy bears for the royal baby.
Mr Cooper and Mrs Kellam also got the chance to mingle with the Duke and Duchess along Kingfisher Bay Jetty.
Sharing an incredible photo to Facebook, Queensland Ambulance Services wrote: "Here's the magic moment The Duke and Duchess of Sussex posed for a happy snap on Fraser Island this afternoon with QAS officers Graeme Cooper and Danielle Kellam.
"The Duke even placed one of the QAS teddy bears the officers had presented to the Royals on Danielle's shoulder."
"It was so incredible," Ms Kellam told 7 News.
"They both seemed sincere."
They said the royals were keen to hear more details about what happened at the time when the photo with the gravely ill patient was taken.
The pair said it was a great honour to be recognised by the royal family, with Mr Cooper citing all the great work Harry has done with the Invictus Games.
But recognition isn't why the pair get up and go to work every morning.
"If I lost my compassion for the public, that would be the day to hang my shirt up because I'd know I wouldn't have what I need to do the job," Mr Cooper told The Courier Mail.
The royal tour will continue on Tuesday, October 23, when the Duke and Duchess of Sussex fly to Fiji.